Methods for well completion



July 4, 1967 E. F. BRIEGER 3,329,204,

METHODS FOR WELL COMPLETION Filed April 29, 1965 Vb Nb I N VEN TOR.

United States l Patent 3,329,204 METHODS FOR WELL COMPLETION Emmet F. Brieger, Needville, Tex., assignor to Schlumberger Well Surveying Corporation, Houston, Tex., a corporation of Texas Filed Apr. 29, 1965, Ser. No. 451,801 5 Claims. (Cl. 166-13) This invention relates to methods for completing Wells; and, more particularly, to methods for inhibiting the production of sand from unconsolidated or incompetent sub-surface earth formations.

The present trend in well completion techniques is to rely upon only one or, at most, a very few perforations at each of carefully selected points in a well rather than indiscriminately scattering a large number of perforations along a wide interval. Where such perforations are made in a particularly loose or unconsolidated formation, sand particles and the like will however, be displaced into the well bore as connate fluids are produced from the formation. Thus, unless preventative measures are taken, these sand particles will either settle out so as to eventually ll the well bore or be carried to the surface by the produced iluids and severely damage production equipment. Moreover, with only a few perforations affording limited entry into the formation, the production will be severely limited should any of these perforations become plugged.

Accordingly, to solve this problem, apparatus and methods have been devised whereby as soon as a loose formation is perforated, a suitable bonding or consolidating agent is injected through the perforation into the formation where, in time, it will react and harden. These agents or so-called plastics generally coat the sand particles and thereby cement them together. Although it will depend upon the particular agents employed, the pore spaces between adjacent particles are left open in one way or another so as to provide permeability. Thus, a portion of the formation surrounding the perforation is consolidated to serve as a porous support to prevent loose sand particles from entering the perforation as connate fluids are produced from the formation.

Typical of such treatting agents, apparatus and methyods are those disclosed in Patents No. 3,153,449, granted to Maurice P. Lebourg, and No. 3,174,547, granted to Roger Q. Fields. As described in those patents, a perforating and injecting tool is positioned adjacent a formation that is believed to be unconsolidated. An extendible wall-engaging means is operated to shift the tool toward one wall of the casing to isolate a portion of the Well bore from the well control fluids. A perforator, such as a shaped charge, is then actuated to produce a perforation through this isolated portion into the adjacent earth formation. Thereafter, a bonding agent is ejected from a cylinder in the tool by a displacing piston and injected through the perforation into the formation.

j The present invention is therefore intended to provide methods for more effectively injecting consolidating agents into an unconsolidated formation and increasing the surface area through which formation fluids are produced. In the practice of the present invention, shaped' charges are employed to open a circuitous ilow passage with a greater surface area. Debris from the shaped charges and particles from the casing and cement are displaced from the iiow passage to expose this increased surface area for more effective production of connate iluids.

Accordingly, it is an object of the present invention to provide new and improved methods for consolidating incompetent earth formations and providing unobstructed 3,329,204 Patented July 4, 1967 and enlarged iiuid passages therein that are free of such objectionable low-permeability debris and have a greater exposed surface area to increase production flow rates.

In one manner of practicing the present invention, this and other objects are provided by first isolating a surface of the casing adjacent to an unconsolidated earth formation from the well control iiuids in a well bore; perforating through the isolated surface into the formation; injecting a formation-consolidating agent through the perforation into the formation under sui'licient pressure to break through debris and enter the formation; injecting a temporary plugging agent into the formations to prevent its collapse; prior to a time at which hardening of the consolidating agent might be expected, perforating through the isolated surface into the treated portion of the formation, the last perforation establishing a circuitous tiow passage through the formation bet-Ween a receiver at low pressure and the source of the plugging agent so that the pressure of the connate fluids will act on the walls of the flow passage and tend to collapse the passage; flushing the ow passage with an additional quantity of plugging agent to remove matter loosened by the connate fluids and enlarge the circuitous ilow passages; and injecting an additional quantity of the plugy ging agent into the passage before the tool is retrieved to isolate the passage from well control fluids after the tool is retrieved and prevent its collapse before the consolidating agent has hardened.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

FIGS. 1-3 are views depicting in sequence a well completion tool within a well bore and practicing the present invention; and

FIG. 4 is a partial view of sealing means for use with the well completion tool in FIGS. l3.

Turning now to FIG. l, 4a well completion tool 10 is arranged for practicing the methods of the present invention and is shown suspended from a multi-conductor cable 11 in a casing 12 secured within a borehole 13 by a column of cement 14. The cable is spooled from a winch (not shown) at the earths surface with some of its conductors being arranged for selective connection to a conventional power source (not shown) and others being connected to a conventional indicating and recording means (not shown) at the surface of the ground.

The well completion tool 10 is comprised of an elongated body 15 which, to facilitate manufacture and assembly, may be arranged to include tandemly connected sections. Longitudinally spaced, annular sealing means 16 and 17 are disposed on one side of the body and extendible and retractble wall-engaging means 18 on its opposite side.

The upper portion of the tool body 15 encloses a hydraulic system (not shown) for selectively actuating the extendible wall-engaging means 18 and other devices within the tool 10. This hydraulic system may, for eX- ample, be of the type illustrated in Patent No. 3,011,554, granted to Robert Desbrandes, which utilizes the hydrostatic pressure of the well control fluids or mud 19 to develop an increased pressure in the system for selectively actuating the wall-engaging means 18. Thus, upon command from t-he surface, the wall-engaging means 18 will be extended against one side of the casing 12 to shift the tool 10 laterally and sealingly engage the sealing means 16 and 17 against the opposite side of the casing. By relieving the hydraulic pressure in the system, the wall-en- 3 gaging means 18 will be retracted to permit retrieval of the tool 10.

The hydraulically actuated wall-engaging means 18 is comprised of one or more extendible pistons 20 that support a backup shoe 21 that is normally held in a retracted position against the body by springs 22. The pistons are sealingly received within hydraulic cylinders (not shown) that are connected to the hydraulic system. Thus, whenever the hydraulic system is activated from the surface, the developed hydraulic pressure will urge the pistons 20 outwardly to extend the back-up shoe 21 against the casing 12. Inasmuch as the particular details of the hydraulic system and wall-engaging means 18 are not necessary for fully understanding the present invention, they have been shown only schematically.

Fluid discharge means are generally housed in the intermediate portion of the tool 10 and include a pair of lateral chambers 23 and 24 therein that are each open at one end, with the chambers being tilted in such a manner that their central axes intersect or approach an intersection a short distance in front of the open ends. The annular sealing means 16 and 17 are mounted around the open ends of these chambers 23 and 24 and provide central openings 25 and 26. The lower chamber 24 is connected to a fluid passage 27 and thin-walled closure members 28 and 29 .are mounted in the chamber on each side of the open upper end of the passage to block the central opening 26 and the rearward portion of the chamber. A shaped charge 30 is received in the rearward portion of the lower chamber 24 and faces the closure members 28 and 29 so that, upon detonation, the perforating jet will puncture the closure members and be directed through the central opening 26.

In a similar manner, the upper chamber 23 is connected by a fluid passage 31 to an enclosed low pressure or atmospheric chamber 32 in the tool body 15. Thin-walled closure members 33 and 34 are mounted in the upper chamber 23 on each side of the open lower end of the passage 31 to block the central opening 25 of the sealing means 16 and the rearward portion of the chamber. A shaped charge is -disposed in the rear of the upper chamber 23 and directed toward the closure members 33 and 34 so that, upon detonation, the perforating jet will pierce the closure members and be directed through the central opening 25. Suitable electrically responsive igniter means (not shown) that are selectively operable from the surface of the earth, via conductors in cable 11, are connected to the shaped charges 30 and 35.

It will be realize-d that when the lower shaped charge 30 is detonated to puncture the closure members 28 and 29 and produce a perforation 36 into an adjacent earth formation 37, fluid communiaction will be established from the iluid passage 27 through the central opening 26 and into the perforation. Similarly, whenever the other shaped charge 35 is denoated, the closure members 33 and 34 will be pierced and fluid communication will be established from the resultant perforation 38 (FIG. 3) through the central opening 25 and into the low-pressure chamber 32.

Separate treating agent cylinders 39 and 40 are formed in the lower portion of the tool body 15. The upper cylinder 39 sealingly receives a slidable, annular, piston member 41 that is sealingly engaged around a concentrically positioned tubular member 42 that extends through the upper cylinder into the lower cylinder 40. The upper cylinder is of a greater volume than chamber 32 and is connected via a centrally located passage 43 and a normally-closed valve (such as that shown 41 in Patent No. 3,121,459) to the passage 27. A port 45 is provided below the annular piston member 41 so that whenever the valve 44 is opened, well control uids 19 can act upon the piston to displace a treating agent from the cylinder 39 through the passage 43 and into passage 27.

The lower cylinder 40 is connected via the centrally located tubular member 42 to a normally-open valve 46 (such as at in the Desbrandes patent) connected to uid passage 27. A treating agent injector 47 is provided for the lower cylinder 40 and is more fully described in a co-pending application by the applicant, Ser. No. 438,872, filed Mar. 11, 1965. The injector 47 is comprised of a slidable, hollow cylinder 48 that has a closed lower end 49 and is telescoped over a piston 50 secured through an elongated coaxial rod 51 to the upper end of the treating agent cylinder 40 and slidably received in the treating lagent cylinder. An annular piston 52 secured to the upper end of the slidable cylinder 48 is fluidly sealed by O-rings 53 and 54 to the inner wall of the hollow cylinder 48 to provide `an enclosed low pressure or atmospheric chamber 56 therein below the fixed piston 50. A port 57 is provided in the wall of the hollow cylinder 48 to admit well control fluids 19 into the space 58 below the annular piston 52 and above the xed piston 50.

The lower treating agent cylinder 40 is divided into separate Huid-tight chambers 59-61 by spaced, floating piston `61 and 63 that are each fluidly sealed between the elongated rod 51 and inner wall of the cylinder 40. As will be subsequentially explained, valves 64 and 65 (such as those shown in FIG. 3 of the Fields patent) in the annular oating piston 62 and 63 remain closed to segregate the treating agents in the chambers 59-61 until each piston 62 and 63 has reached its upper limit of travel. A flow restrictor 66 is placed in series with the valves 64 to regulate the ow of treating agents from the intermediate and lower chambers 60 and 61.

It will be appreciated that when the cylinder 40 is Ailled with treating agents, the hollow cylinder 48 and annular piston 52 will remain in a fully extended position until the thin-walled closure member 28 is punctured. Thus, until the shaped charge 30 is detonated, the forces tending to move the hollow cylinder 48 and piston 52 upwardly must equal the forces acting downwardly thereon. Since each of these forces is equal to the product of a pressure multiplied by the effective cross-sectional area that it acts upon, by reference to FIG. 1, the forces can be expressed as:

It will be appreciated that (A3-A1) will be very nearly equal to A2 and that Pam, will be practically negligible. Thus, it will be realized that the pressure developed (Pdev) in the lower treating cylinder 42 will be very nearly double the hydrostatic pressure (Phyd) of the well control uids 19. Accordingly, if, for example, the ratio of developed and hydrostatic pressure is in the order of 1.8:1 and. the hydrostatic pressure is 10,000 p.s.i.g., it will be appreciated that the injection pressure will be 18,000 p.s.i.g. Thus, if the natural formation pressure is 9,000 p.s.i.g., the treating agents in the lower cylinder 40 will be injected at an effective differential of 9,000 p.s.i.

Accordingly, the hydrostatic pressure of the well -control fluids 19 will act on the injector 47 to exert a multiplied pressure on the treating agents in the chambers 59-61 to sequentially discharge the treating agents from the chambers through the tubular member 42 l'and valve 46 into the fluid passage 27 thereabove. This multiplied pressure produces a high effective differential pressure relative to formation pressure.

The passages 42 and 43 converge above their respective valves 46 and 44 `and are connected to fluid passage 27 leading to the sealing means 17. A pressure transducer '67 is provided to continuously monitor the pressure in the fluid passage 27. This transducer `67 may, for example, be of the type shown in FIG. 9 of the above-mentioned Desbrandes patent, and is connected by an electrical lead (not shown) via the cable 11 to the pressure indicating and recording apparatus lat the surface of the earth. Thus, by observing the variations in pressure measurements, an operator will be advised of the occurrence of various steps in the loperating cycle of the well completion tool 10.y

Pdev

The successive steps of the present invention are schematically illustrated in FIGS. 1-3 as they would be performed by the well completion tool 18. Although the exact arrangements will, of course, be determined by the particular consolidating materials to be used, a pre-flush fluid 68, such as a saline solution, is contained in the upper chamber 59 of lthe lower treating agent cylinder 40. The intermediate chamber "60 contains a plastic consolidation lagent 69, such as a formaline-cresol mixture, while the lower chamber 61 contains an after-hush agent 70, such as kerosene. A suitable temporary plugging agent 71, such as Black Magic oil-base mud as supplied by Oil Base, Inc., of Compton, Calif., is deposited in the upper treating cylinder 39. v

After the treating agents 68-71 have been deposited in the cylinders 39 and 40, the tool 10 is assembled and positioned in the well bore 13 adjacent a selected formation 37. By actuating the hydraulic system, the backup shoe 21 is extended to shift the tool laterally yand sealingly engage the sealing members 16 and 17 against the casing 12. Once the sealing members 16 and 17 have been firmly seated, it will be appreciated that the central openings 25 and 26 in front of the thin-walled closure members 16 and 17 will be isolated from the well control fluids 19 in the well bore 13. By this time, the hydrostatic pressure of the |well control fluids 19 will have displaced the pre-flush fluid 68 from the upper chamber 59 through the normally-open valve 46 and into the space between the thin-walled closure members 28 and 29.

As best seen yin FIG. 1, :the lower shaped `charge 30 is then detonated to puncture the thin-walled closure members 28 and 29 and produce a perforation 36 that is directed into the formation 3,7 in a slightly upward direction. As previously mentioned, debris from the shaped charge 30 and particles of the casing 12 `and cement 14 will be left Iin the perforation 36.

As the perforating jet punctures the `closure member 28, the pre-flush fluid 68 (which is at the developed pressure) will be immediately displaced into the perforation 36. As the pre-flush fluid 68 is exhausted from the upper chamber 59, it will be realized that the substantial pressure differential between the amplified pressure developed in the treating cylinder 40 by the injector 47 and the formation pressure will be available to inject this agent at a high flow rate -into the formation 37. Thus, by injecting the pre-flush fluid 68 into the formation 37 at this elevated differential pressure, the agent will be able to break through loose or encrusted residue left in the perforation 36 by the shaped charge 30 and enter the formation.

As best seen in FIG. 2, once the pre-ush uid 68 has lbeen expelled from the upper chamber 59, the upper floating piston 60 w-ill have reached the top of the cylinder 40 to open the valve 64 therein. Then, the combined application of the developed pressure by the injector 47 will displace the other treating agents 69 and 70 at a regulated flow rate and controlled sequence from the i11- termediate an-d lower chambers 60 and 61 through the flow restrictor 66 and into the formation 37.

It has been found that by initially injecting the treating agents (such as the pre-Hush fluid 68) at a high flow rate and pressure, loose sand cannot flow back into the tool and the perforation 36 will be prevented from collapsing. It has been found advantageous, however, to inject the other treating agents 69 and 70 more slowly and at only a sufficient pressure differential over the formation pressure that the agents will not channel but will instead permeate and uniformly ll the voids between the individual sand particles. It will be understood, however, that the full developed pressure of the injector 47 is always available; and, where a greater pressure differential is needed, the flow rate will be reduced by the restrictor 66 as the pressure downstream thereof increases.

Once the treating agents 68-71 have been exhausted, andas best seen in FIG. 2, before the plastic consolidating material 89 has hardened, the normally-closed valve 44 is opened. Valve 46 may be closed at this time if desired. This will permit the hydrostatic pressure of the well control fluids 19 to act through port 4S and urge piston 41 upwardly. The plugging agent 71 will be injected into the perforation 36 until a suicient filter cake (which is relatively impermeable) has been built up on the wall of the perforation to block the further flow of the agent. It will be understood, of course, that the piston 41 will keep the perforation 36 full of the plugging agent 71 and maintain the agent at hydrostatic pressure.

As best seen in FIG. 3, the upper shaped charge 35 is detonated to produce the second perforation 38 that either intersects the first perforation 36 or cornes in close proximity thereof. It will be appreciated that the second perforation 38 will be oriented to be effectual for suddenly establishing fluid communication from the first perforation 36 to the atmospheric chamber 32. A normally-closed valve could, of course, be provided in passage 31 to control this fluid communication. In any event, however, when communication is opened from the treating cylinder 39 to the atmospheric chamber 32, the differential pressure of formation fluids tends to collapse the perforations and dislodge debris filter cake into the perforations 36 and 38 toward the atmospheric chamber, At the same time, the connate uiids .and plugging agent 71 will sweep or flow through the perforations 36 and 38 into the atmospheric chamber 32. It has been found that the sudden irl-rush of the connate fluids and plugging agent 71 will flush the ydebris from within the perforations 36 and 38 and leave their wall surfaces relatively uncontaminated. Moreover, laboratory tests have shown that this sudden in-rush of the plugging agent 71 will often enlarge the formation 37 around the junction of the perforations 36 and 38 to provide a cavity therein such as at 72. Then, once the low-pressure chamber 32 has filled, the plugging agent 71 will permeate into the formation 37 until a filter cake again builds up on the walls of the cavity 72. Then, the tool 10 can be lremoved and the hydrostatic pressure of the well control tiuids 19 acting on the plugging agent 71 will support the cavity 72 to prevent its collapse while the sand consolidating agent 69 is hardening.

It will Ibe appreciated that once the sand consolidating agent 62 has hardened, a porous support, such as at 73,

will be formed around the perforations 36 and 38 and cavity 72. This porous support 73 will, of course, provide a substantial surface area through which conn-ate fluids can flow that nevertheless restrains the loose unconsolidated formation particles therebeyond.

Once the treat-ing operation has been completed, the hydraulic system is actua-ted to relieve the hydraulic pres- `sure therein to retract the back-up shoe 21 and allow the tool 10 to be withdrawn from the well bore 13. It will be understood, of course, that although the'tool 10 is withdrawn, ythe well control fluids 19 will continue to maintain the plugging agent 71 inthe cavity 72 until the porous support 73 has become consolidated.

Accordingly, it will be seen that to practice the abovedescribed method of the present invention, the tool 10 is positioned in the -borehole 13 adjacent to the formation 37 of interest. The sealing means 16 and 17 Iare urged against the casing 12 to isolate a surface from the well control fluids 19. Then, the formation 37 is perforated, as at 36, through the isolated surface to permit injection of formation-consolidating agents, such as plastic 69, into the formation which, in time, will harden to form a porous support, as at 73, adjacent to the entry hole through the casing 12. A temporary plugging agent, such as at 71 is injected into the perforation 36 at a pressure greater than formation pressure to prevent the collapse of the perforation 36. Thereafter, the formation 37 is again perforated, as at 38, through the isolated surface to open communication 4from the first perforation 36 to a low pressure chamber, lsuch as at 32, for receiving the plugging agent 71 to flush the perforation and cut out a cavity 72 in the formation while sti-ll maintaining sufficient pressure against the walls of the cavity to prevent its collapse. Finally, a further quantity of plugging agent 71 is introduced into the cavity 72 before the tool 10 is withdrawn to prevent collapse of the cavity until the porous support '73 has hardened.

Turning now to FIG. 4, a partial view is shown of one embodiment of sealing means 100 that may be employed with tool for sealing off an area of the casing 12. The sealing means 100 is adapted to be threadedly secured and fluidly sealed in the forward portion of the shaped charge chambers to isolate the shaped charge therein. Thus, the sealing means 100 is comprised of a threaded tubular member 101 having an enlarged-diameter flange 102 on its forward end. The flange 102 supports a pair of elastomeric sealing members 4103 and 104 and is adapted for reception within a forwardly facing counterbore (not shown) in the tool 10 and fluidly sealed therein 'by O-rings 105 and 106. `O-rings 105 and 106 around the central portion of the tubular closure member 101 provide a fluid-tight annular space within the forward end of the shaped charge chamber that is connected by radial bores 107 and 100 to the central bore 109 through the tubular member.

The sealing members 103 and 10d are concentrically arranged on opposite sides of an annular reinforcing member y110. A shoulder 111 directed inwardly from the rear of the reinforcing member 110 is secured against the forward face of the tubular closure member 101 by the forward thin-walled closure member 102. The forward faces of the sealing members 103 and 104i are .skewed in the vertical plane and curved in the horizontal plane to ensure that they will conform to `the curvature of a casing wall.

Thus, it will be appreciated that the reinforcing ring 103 will prevent the outer elastomeric ring 103 from being extruded radially inwardly whenever ythe hydrostatic pressure of the well control fluids is greater than pressure Within the central opening 113. Similarly, the inner elastomeric ring 104 will ibe supported against extrusion radially outward-ly Iwhenever the pressure within the central opening l113 is greater than that of the well control fluids.

The thin-walled closure members 112 and 114', are spaced apart and threadedly secured in the central bore 109 through the tubular closure member 101 on opposite sides of the radial bores 107 and 108 to block the central `opening 113 and isolate the .shaped charge therebehind.

The plastic consolidation agents used in practicing the present invention may be either porous-setting or solidsetting plastics. The invention is not limited, however, to any particular type of sand-consolidating agent so long as it is capable of ultimately providing a porous barrier within the formation around the perforation through which it is ejected. Typical types of sand consolidation agents that may be used generally include (1) poroussetting types of plastic wherein a phase separation takes place to leave hardened plastic around the sand grains and open pore spaces between the sand grains; (2) porous-setting types of plastic that shrink and crack upon hardening to form openings within .the consolidated zone to allow passage of connate fluids; (3) solid-setting types of plastic wherein after the plastic is injected, after-flush fluids are injected to wash away the plastic from the pore spaces between sand particles to provide suflicient permeability yfor flow of connate fluids; and (4) solid-setting types of plastic wherein some of the constituents 'are kept separated from one another iwithin the treating agent cylinder and are successively injected into the formation to mix in situ.

It will be further appreciated that the particular nature of the sand-consolidating agent employed will govern whether additional agents such as a pre-flush or an afterilush are required. Thus, the treating cylinder 40 needs only to contain the essential agents or constituents thereof and may be arranged in whatever sequence that are considered to be necessary to obtain a porous consolidated portion.

Accordingly, `the present invention should neither be considered as being limited to any particular one or genus of sand-consolidating agents nor as requiring preflush or after-flush fluids unless necessary to achieve the above-mentioned firming reaction.

Thus, it will be appreciated that the present invention has provided new and improved methods for providing enlarged fluid .passages into unconsolidated earth formations that are supported :against collapse and are free of objectionable low-permeability debris so that materials may be injected into the formations at reasonably high flow rates. Moreover, it should be realized that increased production will be obtained iby practicing the methods of the present invention by providing `an increased surface area through which production will flow and an enlarged, unobstructed passage for such production.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made Without departing from this invention in its broader aspects, and, therefore, the aim of the appended claims is to cover all such changes and modifications as fall -within the true spirit and scope of this invention.

What is claimed is:

1. A method of completing a cased well bore containing a column of well control fluids and traversing an earth formation containing connate fluids and believed to include unconsolidated particles, comprising the steps of: packing-off first and second portions of the casing to isolate said first and second portions from one another and from the well control fluids; perforating through the casing at said first isolated portion and into the formation to provide a first passage therein; injecting a hardenable formation-consolidating agent into said first passage at a pressure sufficient to break through debris in said first passage and enter the formation for consolidating unconsolidated particles within the formation; injecting a temporary plugging agent into said first passage; prior to a time calculated to be sufficient for hardening of said consolidating agent, perforating through the casing at said second isolated portion and into the formation in a direction relative to said first passage to provide a second passage therein effectual'for establishing fluid communication with said first passage; reducing the pressure in said second isolated portion for producing connate fluids from the formation to dislodge debris from the walls `of said passage; and injecting additional plugging agent through said first isolated portion into said passages for flushing debris therefrom and forming a filter cake on said passage wall.

2. A method of completing a cased Well bore containing a column of well control fluids and traversing an earth formation containing connate fluids and believed to include unconsolidated particles, comprising the steps of: packing-ofic first and second portions of the casing to isolate said rst and second portions from one another and from the well control fluids; perforating through the casing at said first isolated portion and into the formation to provide a first passage therein; injecting a hardenable formation-consolidating agent at a pressure greater than the hydrostatic pressure of the well control fluids through said first isolated portion and into the formation for consolidating unconsolidated particles within the formation; injecting a temporary plugging agent into said first passage; prior to a time calculated to be sufficient for hardening of said `consolidating agent, perforating through the casing at said second isolated portion and into the formation in a direction relative to said first passage to provide a second passage therein effectual for establishing fluid communication with said first passage; reducing the pressure in said second isolated portion for producing connate fluids from the formation to dislodge debris from the Walls of said passages; and injecting additional plugging agent through said first isolated portion into said passages for flushing debris therefrom and forming a filter cake on said passage walls.

3. A method of completing a cased Well bore containing a column 4of well control iiuids and traversing an earth formation containing connate fluids and believed to include unconsolidated particles, comprising the steps of: packing-off first and second portions of the casing to isolate said first and second portions from one another and from the Well control fiuids; perforating through the casing at said first isolated portion and into the formation to provide a first perforation therein; injecting a hardenable formation-consolidating agent at a pressure greater than the hydrostatic pressure of the well control fluids through said first isolated portion and into the formation for consolidating unconsolidated particles within the formation; injecting a temporary plugging agent into said first perforation; prior to a time lcalculated to be sufficient for hardening of said consolidating agent, perforating through the casing at said second isolated portion and into the formation in a direction calculated to approach an intersection with said first perforation to provide a circuitous flow passage therein in fluid communication between said first and second isolated portion; reducing the pressure in said second isolated portion for producing connate fiuids from the walls of said circuitous flow passage; and injecting ad ditional plugging agent through said first isolated portion into said fiow passage for ushing debris therefrom and forming a filter cake on said passage Walls. t

4. A method of completing a cased well bore cont-aining a column of Well control uids and traversing an earth formation containing connate fluids and believed to include unconsolidated particles, comprising the steps of: packing-off first and second portions of the casing to isolate said first and second portions from one another and from the well control fiuids; perforating through the casing at said first isolated portion and into the formation to provide -a first passage therein; injecting a first agent into said first passage at a first iiow rate and pressure sufficient to break through debris in said first passage; injecting a ow rate consolidating agent at a con-trolled second flow rate into said first passage and into the formation for consolidating unconsolidated particles Within the formation, said second iiow rate being no greater than said first flow rate; injecting a temporary plugging agent into said first passage; prior to -a time calculated to be sufiicient for hardening of said consolidating agent, perforating through the casing at said second isolated portion and int-o the formation in a direction relative to said first passage to provide a second passage therein effectual for establishing uid communication with said first passage; reducing the pressure in said second isolated portion for producing connate fluids from the formation to 10 dislodge debris from the walls of said passages; and -injecting additional plugging agent through said first isolated portions into said passages for iiushing debris there'- from and forming a filter cake on said. passage Walls.

5. A method of completing a cased Well bore containin-g a column of well contr-ol fiuids and traversing an earth formation containing connate fluids land believed to include unconsolidated particles, comprising the steps of: packing-off first and second portions of the casing to is-olate said first and second portions from one another and from the well control fiuids; perforating through the casing lat said first isolated portion and into the formation to provide a first perforation therein; injecting a first agent into said first perforation at a first flow rate and a pressure sufiicient to ybreak through debris in said first perforation; injecting a hardenable lformation-consolidating agent at a regulated second flow rate and la pressure greater than the hydrostatic pressure of the well control fluids through said first isolated porti-on and into the formation for consolidating unconsolidated particles within the formation, said second flow rate being less than said first flow rate; injecting a temporary plugging agent into said first perforation; prior to a time calculated to be sufficient for hardening of said consolidating agent, perforating through the casing at said second isolated portion and into the formation Vin a direction calculated to yapproach an intersection with sai-d first perforation to provide -a circuito-us fiow passage therein in fiuid cornmunication between said first and second isolated portions reducing the pressure in said second isolated portion for producing connate fluids from the formation to dislodge debris from the walls of said circuitous flow passage; and injecting additional plugging agent through said first is-olated portion into said flow passage for flushing debris therefrom and forming Va filter cake on said passage Walls.

References Cited UNITED STATES PATENTS 2,769,498 111/1956* Huber 166-23` X 2,821,256 1/1958 Boller 166--100 X 3,070,160 12/ 1962 Reis-tie 166-22 X 3,115,932 12/1963 Reynolds 175--452 3,121,459 2/1964 Van Ness et al. 166-23 X 3,153,449 10/1964 Lebourg 166-35 X 3,174,547 3/'1965 Fields 175-4 3,273,647 9/1966 Briggs et al 166-100 CHARLES E. OCONNELL, Primary Examiner. D. H. BROWN, Assistant Examiner. 

1. A METHOD OF COMPLETING A CASED WELL BORE CONTAINING A COLUMN OF WELL CONTROL FLUIDS AND TRAVERSING AN EARTH FORMATION CONTAINING CONNATE FLUIDS AND BELIEVED TO INCLUDE UNCONSOLIDATED PARTICLES, COMPRISING THE STEPS OF. PACKING-OFF FIRST AND SECOND PORTIONS OF THE CASING TO ISOLATE SAID FIRST AND SECOND PORTIONS FROM ONE ANOTHER AND FROM THE WELL CONTROL FLUIDS; PERFORATING THROUGH THE CASING AT SAID FIRST ISOLATED PORTION AND INTO THE FORMATION TO PROVIDE A FIRST PASSAGE THEREIN; INJECTING A HARDENABLE FORMATION-CONSOLIDATING AGENT INTO SAID FIRST PASSAGE AT A PRESSURE SUFFICIENT TO BREAK THROUGH DEBRIS IN SAID FIRST PASSAGE AND ENTER THE FORMATION FOR CONSOLIDATING UNCONSOLIDATED PARTICLES WITHIN THE FORMATION; INJECTING A TEMPORARY PLUGGING AGENT INTO SAID FIRST PASSAGE; PRIOR TO A TIME CALCULATED TO BE SUFFICIENT FOR HARDENING OF SAID CONSOLIDATING AGENT, PERFORATING THROUGH THE CASING AT SAID SECOND ISOLATED PORTION AND INTO THE FORMATION IN A DIRECTION RELATIVE TO SAID FIRST PASSAGE TO PROVIDE A SECOND PASSAGE THEREIN EFFECTUAL FOR ESTABLISHING FLUID COMMUNICATION WITH SAID FIRST PASSAGE; REDUCING THE PRESSURE IN SAID SECOND ISOLATED PORTION FOR PRODUCING CONNATE FLUIDS FROM THE FORMATION TO DISLODGE DEBRIS FROM THE WALLS OF SAID PASSAGE; AND INJECTING ADDITIONAL PLUGGING AGENT THROUGH SAID FIRST ISOLATED PORTION INTO SAID PASSAGES FOR FLUSHING DEBRIS THEREFROM AND FORMING A FILTER CAKE ON SAID PASSAGE WALL. 